Source?
I am sure there are many more sources out there.
Slightly clarification to OC’s remarks. The original contract was for $700 (so Jobs didn’t lie there). However, what Jobs kept secret is that there was a substantial bonus for reducing the amount of chips needed. Wozniak was specially good at optimizing the amount of chips in a circuit so the end design used substantially fewer chips and hence the bonus was much bigger than the amount agreed before.